The effect of ACTH on cholesterol binding to adrenal mitochondria cytochrome P-450 will be studied. The possible role of a phosphorylated protein in this interaction will be evaluated. These studies will be extended to the guinea pig in order to evaluate the action of ACTH on a cortisol secretor. Related studies of this cytochrome P-450 system will be conducted with zona glomerulosa tissue in order to examine the control of aldosterone biosynthesis. These latter studies will be concerned with the effect of agents such as ACTH, sodium, potassium and angiotensin II on the "early" and "late" pathway for aldosterone synthesis. The overall control of steroidogenesis during the diurnal rhythm of adrenal activity in the rat will be examined. BIBLIOGRAPHIC REFERENCES: Temperature Dependence of Cholesterol Binding to Cytochrome P-450 of the Rat Adrenal: Effect of ACTH and Cycloheximide. Douglas P. Paul, Samuel Gallant, Nanette R. Orme-Johnson, William H. Orme-Johnson, and Alexander C. Brownie. J. Biol. Chem. 25l:7120-7126, 1976. Effect of ACTH on Cytochrome P-450 Systems of the Adrenal Cortex. Alexander C. Brownie, Samuel Gallant, Douglas P. Paul, Lloyd L. Bergon, Nanette R. Orme-Johnson, and William H. Orme-Johnson. New York Academy of Sciences, In Press, 1977.